Class Libraries & REST APIs for the developers to manipulate & process Files from Word, Excel, PowerPoint, Visio, PDF, CAD & several other categories in Web, Desktop or Mobile apps. Develop & deploy on Windows, Linux, MacOS & Android platforms.... add ( "header 1" ) row . cells . add ( "header 2" ) row ....cells . add ( "header 3" ) row . cells . add ( "header 4" ) row ....